This invention relates generally to magnetic tape drive mechanisms, and more particularly, to reel-to-reel tape drive mechanisms, in which tape is driven from a supply reel to a take-up reel, and in which the supply reel is removable. In one specific type of reel-to-reel tape drive, the tape is driven by an endless drive belt engaging wound tape packs on both tape reels. Regardless of the method used to drive the tape from one reel to the other, reel-to-reel tape drives should ideally be self-threading, i.e. it should be possible to thread the tape automatically from the supply reel to the take-up reel, without operator intervention.
The usual approach is to employ a tape picker in conjunction with a relatively stiff tape leader. The tape leader is structured to be easily retained on the supply reel, such as by making it somewhat wider that the space between the reel flanges, or by including an adhesive on its lower surface. In any event, the tape leader is removably retained on the supply reel in a manner as to prevent inadvertent unraveling of the tape. The tape picker is a sharply tapered element, having a relatively sharp edge that is brought into contact with the periphery of the supply tape pack, to pick the leader from the pack and guide it in a desired direction, usually through a tape guide channel and into a position from which it can be captured by some mechanism for wrapping the tape about the take-up reel.
Once threading of the tape has been accomplished, the picker must be retracted from the tape pack, to prevent any unwanted resistance to the rotation of the supply reel. The normal technique for tape picking is to mount the picker on an arm that is movable in response to actuation of a solenoid. The solenoid is actuated only at the time that tape threading is to take place, after which it is deactivated to allow the picker to be retracted, by spring action, from the tape pack. Although this technique is satisfactory for most applications, it requires appropriate control circuitry to ensure that it will be operated at the proper time. Moreover, the need for a solenoid places a constraint on the use of space within a tape drive. For drives that are to be accommodated in limited space, there simply may not be room to provide a solenoid-actuated picker of the conventional type.
Accordingly, there is still a need for an improved tape picker, preferably one that functions automatically without the need for solenoids or other electrical components. The present invention satisfies this need.